Fuel economy and safety are of high interest in connection with motor-vehicles. In many familiar motor vehicles an internal combustion engine is the prime mover for powering a drivetrain that extends to the wheels, thereby to move the vehicle across a surface such as a road. In addition to moving the vehicle, the engine is often used to power equipment such as power-assisted steering and vacuum-assisted power brakes. Some vehicles have an air compressor which is driven by the engine, to provide compressed air for operation of components such as brakes.
Pressurized hydraulic fluid aids the operator in movement of a steering wheel, for directing the vehicle. If hydraulic power is suddenly absent, turning the vehicle's steering wheel can be dangerously difficult.
Vacuum to power a brake booster is commonly obtained by connection to the sub-atmospheric pressure region within the intake manifold of the internal combustion engine. If the engine is stopped, with the result that the vacuum source is absent from a typical braking system, the vehicle's braking action can be dangerously reduced.
Some motor vehicle operators are known to save fuel by turning off or idling the vehicle's engine, and coasting the vehicle. However, any resultant lack of power to the steering and brake systems can be unsafe. Thus, when a motor vehicle of the type of current interest is coasting, the engine must be kept running at speed sufficient to provide the means for powering brakes and steering, unless there is some sort of hydraulic/pneumatic storage system such as an accumulator or bulky storage tank. Keeping the engine running during conditions when the drivetrain does not require power might be considered an unnecessary expenditure of fuel if there were means other than the engine for ensuring steering and braking safety.
Apparent prior art solutions to the problem of engine failure and resultant inadequate hydraulic system pressure are disclosed in the patent literature, in connection with steering systems on construction and agricultural equipment. Those solutions include providing a hydraulic pump which is powered by contact with the ground (and thus by movement of the vehicle) or a hydraulic pump which is powered by an electric motor. The prior art pumps are said to manually or automatically come on when the primary hydraulic system becomes inoperative because of failure of the hydraulic system or of the engine. See U.S. Pat. No. 3,153,462 of Peller, U.S. Pat. No. 3,940,931 of Renfro et al., U.S. Pat. No. 5,201,174 to Barber et al., U.S. Pat. No. 4,942,935 of Lech, and U.S. Pat. No. 5,564,516 of Nimblett Jr. et al. Deficiencies or limitations in the prior art include that certain prior art inventions are not suited for retrofit, or are only usable momentarily in emergency situations.
There is a need for improvements in internal combustion motor vehicle systems to maintain safety while enabling energy savings. Any improvement should be simple, inexpensive, and preferably appropriate both as original equipment and retrofit on vehicles already in use.